Genetic malfunction
by KenzieTheCrazy
Summary: In the world of Serena Katzberg's dreams, John Harrison, the chief bioengineer on the USS Enterprise, is a terrorist. She can barely tell what's real and what's not anymore. But is she really going insane or there's something her boyfriend is hiding from her? - Khan/OC, AU
1. Dreams

**[DREAMS]**

She had been there for almost fourteen hours now, only leaving the building to eat something for lunch. And, once again, her communicator went off, its sound echoing between the spacious lab's walls. Apart from the guards there were only a handful of people scattered across the building, but the only one Serena cared about was working in the other end of the floor.

Letting out a tired sigh she walked over to him, not bothering with knocking. The door slid open, revealing a man sitting behind a table in the middle of the blindingly white lab. For a second Serena let her gaze stop and linger on the back of his black shirt, seeing the muscles through the thin material, but soon turned away and cleared her throat.

"You know, Harrison, I'm not your maid or assistant," she stated as she walked closer, standing right in front of him with arms folded over her chest. When his blue eyes finally looked up at her, Serena shook her head and said, "I want to go home soon, so what is it now?"

Harrison didn't say anything, only pushed a PADD over to her without breaking eye contact. She ran through the text then put it back down in front of him with a sarcastic laugh. Seconds passed without either of them speaking up, but soon enough he broke the silence.

"I need these things as soon as it's possible," he stated seriously.

"Well, I guess you'll have to wait until you can find someone to do the shopping for you tomorrow," Serena replied with a shrug. When the man slightly tilted his head to one side, she sank down on the chair behind her and crossed her legs. "I helped you before but it doesn't mean you're my boss now. If you need help again, all you have to do is asking me. Nicely," she added quickly.

With an arrogant smile on his face, Harrison stood up and looked down at her with his hands behind his back. "I can still contact Admiral Marcus," he informed Serena coldly as he walked over to her side of the table, making her stand up as well. "I'm sure he would be more than willing to give you an order to be my assistant in the next couple of months."

The lack of the previously safe proximity intimidated her and she couldn't help but take a few steps back. "Why me?" she asked weakly.

"Do I need a reason?"

"Actually, if you would even talk to Marcus just to make me," Serena replied, her voice becoming more confident, "then yes."

* * *

"Serena, wake up."

John's deep voice and his long fingers on the side of her face made her give in and finally open her eyes. He was crouching next to her side of the bed, already wearing his blue uniform, and his bright blue eyes were looking down at her, accompanied by a warm smile. Serena quickly put her hand in front of her mouth as she yawned and stretched her other arm.

"Good morning, Sleepyhead," he said after he sat on the side of the bed. "You should get up so we can have some breakfast before our shift starts."

Of course, it was the Enterprise, not Earth, not London. But the dream seemed so real. Again. It had started roughly a month after they left the planet for the first five-year mission in the history of the Federation. In every single dream she was on Earth, working in some nameless building with John Harrison; _her_ John Harrison, but he wasn't himself. He was cold and arrogant and demanding, no sign of the kindness in his eyes that she loved so much.

Then she woke up and it usually took her a few minutes to get used to the idea it was nothing more but a dream. It wouldn't have bothered her if she wasn't spending most of her nights with John, because whenever dream-John was cruel to her, she found it a bit hard to get used to the idea that real-John was one of the nicest people she had ever met.

"Morning," she said with a small smile while she sat up and gave him a quick kiss. "How was your sleep?"

"Short," came his reply as he flashed a mischievous smile at her. "And it's not my fault since it was _you_ who kept me awake." Serena tilted her head to the side and gave him a disapproving look. Sure, now it was her fault. "I'm only responsible if you're late from your shift," he pointed out before adding, "Or if our plans for the evening are completely ruined."

"Enough," she said with a carefree laugh then stood up on the bed. The only piece of clothing on her was her black panties but she didn't care about that. Not with him. He was so handsome, so intelligent that sometimes she couldn't even imagine what he saw in her, but most of the time she was happy to have him around and she was more than happy to please him. "By the way, how about having lunch together?"

John stood up and turned to face her, his fingers caressing the skin on the sides of her waist as he leaned close to her. "I'm sorry, but not today," he murmured quietly as he placed kisses across her collarbone. "I think I'll work pretty late so I won't even go over to your quarter for the night."

"No problem."

"Sure?" he asked, glancing up at her.

"Yes," Serena stated with a reassuring smile as she jumped off the bed with her arms around his neck. "I'm a big girl, John, I can sleep alone."

He wanted to say something but his communicator interrupted him so he let out a sigh and left to answer it. Serena listened to the conversation, keeping eye contact with him the whole time, even flashing a small smile at the man when she heard he wasn't about to have breakfast with her because there was some kind of a problem in his lab.

After she quickly got dressed and kissed him goodbye, Serena went to the sickbay instead of the mess hall, hoping she would find Dr. McCoy there so early in the morning. Most mornings he was there, enjoying the quiet hours when he had the entire place mostly to himself. But this morning he was in his office, resting his head on his arms while he was sleeping peacefully. She hated herself for doing this, but eventually she knocked on the wall next to the open door and waited for him to wake up.

The doctor raised his head to look at her, fighting back a yawn. "Sorry for waking you up, Bones, but do you have a minute for me?"

"Sure, what's wrong?" Bones asked as he sat up straight and pointed at the chair across from him.

Serena sat down and ran a hand through her long brown hair. _Maybe it wasn't a good idea after all_, she thought. But it was too late now. "The dreams I was talking about two weeks ago," she started. "They are getting more frequent lately; I mean I dream the same thing every other night. And when I say "the same thing", it means it takes place in the same twisted world."

"Probably you're just stressed and tired."

"Stressed? About what? I'm working with computer systems and programs all day long. It's a completely peaceful job," she added just to make it clear. She did love her job.

"Then I don't know, Serena." There was a short pause. Bones looked up at the ceiling for a second and this usually meaningless movement alarmed her. Then he spoke up. "Is everything okay between you and John?" he asked, his hazel eyes now fixed on her.

"Of course," she replied without thinking but then it struck her. Okay? Everything was perfect; maybe too perfect, but she couldn't start talking about it as if that was a problem. This is what Bones was implying, that maybe something was wrong between them? "Wait, you think I'm dreaming about a completely different John because something's wrong between us?" she suddenly asked just to make sure she didn't misunderstand it.

Bones shrugged. "I'm just guessing."

"You know, I'm just worried because these dreams feel so real. God, I'm scared that I might be going crazy."

"Listen, I'll talk to Jim and tell him you're taking a few days off," he finally said, resting his elbows on the desk and resting his chin on his folded fingers. "Doctor's orders, but you have to promise me you'll have some rest. If things won't change after that, we'll talk again."

This sounded way better. Maybe he was right and she did need some time for herself. "Okay, I promise I'll relax," she nodded with a smile. "But now I'll let you sleep or go have something to eat. Thanks for the chat and I'm really sorry for waking you up," Serena said before she turned around and headed towards the mess hall.

* * *

**Author's note:** So I was bored and this idea is the result. I'm really interested in what you think so far.


	2. Time

**Author's note:** Wow, thank you for the reviews! You're awesome and I'm sorry for not replying to all of them!

* * *

**[Time]**

A few days after their quite weird conversation Serena found herself sprawled out on the couch John had in his private lab more and more frequently. Sometimes she wondered if he was human at all, because he was almost always working, day and night, barely sleeping or eating. And this, thanks to Admiral Marcus, made the lab her second home, giving her no time to go back to her own apartment and have some proper rest alone. She had even spent her birthday working which was pretty unusual; in the last couple of years she usually spent those nights at a party and getting drunk with her friends.

At first she'd had no idea what he was working on since it was classified, but as his assistant Serena eventually found out that John Harrison was designing weapons and a brand new ship for Starfleet. Admiral Marcus was the one who told him to do that, in the name of the Federation, the very same organization that was trying to prevent wars, choosing more diplomatic ways for the sake of peace. Now he believed the Klingons were a real threat to them and it was better to be safe than sorry.

Serena soon realized there was something between the admiral and her new boss because from the very beginning it had been her job to keep in contact with Marcus. In the meantime she tried to understand John, his behavior, how to talk to him without enraging him, then finally Serena got a very own project to work on: the new ship's computer system. John had his own ideas, what he wanted to see, but combining it with all the standards and possibilities was her responsibility from that point on.

A month had passed. She barely knew what time it was anymore and even had a suitcase full of clothes in the lab. It had been days since she had last talked to someone other than John or Marcus and Serena was becoming edgy by this. John asked her something, she cursed, he told her to stop and she accidentally threw something at him. But, for her biggest surprise, he barely got mad at her. Not in the beginning, when she didn't ask him about the details of Marcus' plan.

Strangely enough every once in a while he seemed to appreciate her work. Serena wondered why he said these things since usually he was complaining about the useless mind of average humans. Probably he was the kind of genius that considered himself superior to everyone else and this is why she never felt sad if he didn't say a good word to her for days.

It had been almost three months and Serena didn't even have the opportunity to go home anymore. John had, out of nowhere, sent a message to Admiral Marcus, asking him to provide an entire floor to him with their separate quarters so they could work without being bothered by others. She knew she was a prisoner. It had taken her some time to realize it but once she was forced to move in it became clear. It was supposed to be a golden cage, the chance of working on a confidential project for Starfleet, one that would later become legendary.

Even if she was now living in that building, spending her days on that prison-like floor, there were times when she was dying for some time on her own, preferably far away from John, the project and even Starfleet. A normal life; spending time with people who mattered to her, having a good time and enjoying the last years of her twenties.

"I need a day off," she tried once, standing on the other side of his table with her hands behind her back. "I've already told you like a million times that it's my mother's birthday, something I can't miss," she explained, but he didn't seem to listen.

John looked up at her, his blue eyes watching her without the merest hint of emotions. "And, if I remember correctly, I've already said no," he stated.

"But-"

"Serena, no," he interrupted her angrily. "When we finished our job, you might leave, but now we have to work on the ship."

"The ship, right," she said with a small laugh. "Because designing a ship to fight a nonexistent war is much more important than giving me one bloody day off."

He suddenly stood up and reached over the table, putting his large hand around her throat. Pulling her closer, not caring if she could breathe or not, John leaned forward. "Marcus gave me permission to decide when you can leave. He wants results, as soon as it's possible, and this is exactly why I want to keep you around."

Serena put her hands on his wrist, trying to make him let go of her throat, but it was useless. "You never... seemed happy... to... work for him," she said, feeling his grip loosen. "It's like... he's forcing you, too."

"You don't know anything," he replied as he let go of her and walked away. "And I'm not forcing you. I'm barely giving you the opportunity to be a part of this," he added.

And it went like this, every single time he talked about why working on this project was good for her career, but never went further than this, never even mentioned why _he_ wanted to work on this. She even broke into the classified files of Section 31, only to find out more about his past and what did she find? Nothing. Absolutely nothing. No sign of John Harrison existing in the past.

* * *

Having a couple of days off... It had only been a few hours into day one but Serena was already going insane in her quarters. She had obediently taken the sleeping pills Bones gave her the night before, and even slept for almost twelve hours straight, but it didn't seem to be enough. If anything, she was more tired than before. Sleeping pills only intensified the dreams, making them longer, giving her no chance to wake up and get out of that world.

And the more she slept the bigger the difference between real-John and dream-John became. Three or four days had passed without meeting John because he was too busy working on his project and she wanted to be alone, making sure his presence didn't trigger her memories of the aggressive tyrant in her dreams. She didn't want to hate him so it was safer this way for both of them.

But eventually John decided to ignore her request and one day he showed up in her room with some cake that he gave her as an apology. "I don't know what I've done, but I'm sorry," he said before adding, "And I believe you owe me an explanation, something better than being tired and having those nightmares."

"Maybe it was a bad idea," Serena started quietly after he sat on the edge of her bed, trying to reach for her hand that she immediately pulled away.

John gave her a confused look. "What are you talking about?"

"Us," she replied. "I mean we are stuck on this ship for five years and if anything goes wrong between us... I don't want to spend the rest of our time here being on bad terms with you."

He didn't like this idea and neither did she, but there was no other solution. In the end John agreed to give their relationship a break - of course, she would have preferred an actual break-up, but that was just as good for a while. Only a few hours later Bones came to check on her, already aware of the result of her previous conversation with John, and he agreed that this was the best solution at the moment, given their current situation on the ship.

A week had passed since their agreement and they were both working a lot more, spending most of their times in different parts of the Enterprise. Serena was working with Scotty who tried to fix one of the servers she needed to continue her job. It had taken the engineer hours to find the problem, but eventually the screen she wanted to see came to life and he could finally stand up to stretch his arms and legs.

When Serena took a closer look at the computer system's part that she intended to work on, she noticed it wasn't the one she was supposed to find there. For a second she closed her eyes and rubbed the bridge of her nose, hoping she was only tired, but when she looked back, it was still the same. "Scotty, why do I see the system they used on the USS Vengeance instead of what we use on the Enterprise?"

"What are you talking about?" he asked as he crossed the room, looking at the screen over her head.

"Just look at the screen, it's not right," she said, pointing at the device. "It's not supposed to be here."

"From what I see it's the same as before," Scotty shrugged. "How would you know if t was the USS Vengeance's system anyway? Even I didn't have the chance to take a look at that before the ship crashed and Khan destroyed everything when the bomb went off in London."

She couldn't believe it. Of course the engineer was working on completely different parts of the ship but every once in a while even he met the interface of the system and he should recognize the difference right away. It was nothing like the one they were supposed to use yet he failed to see her point. That system, the very same she was now looking at, was far more sophisticated in every sense of the meaning.

After a few seconds she turned around and shook her head as she gave the Scottish man a doubtful look. "Are you kidding me, Scotty? It's an entirely different system, how can you tell me it's the same?" she asked, her voice becoming hysterical by now.

"Serena, is everything okay with you?" the engineer asked seriously, pointing at one part of the screen after pushing a few buttons. "Look, it says USS Enterprise," he read out loud before turning his gaze back to her.

She looked at the screen but it said USS Vengeance, not Enterprise. "It's not funny," she stated in response. He was either playing some stupid game with her or she was going crazy. Knowing Scotty, it could easily be the first option. "Why don't you just tell me how you got your hands on the system?"

Scotty froze then slowly backed away from her. He didn't say anything at first, reaching into his pocket to pull out his communicator. "I'll call Dr. McCoy now," he informed her quietly.

"Scotty, come on, put that away," she told him, "there's nothing wrong with me. I admit, it was a good prank but you can stop now."

* * *

**Author's note:** So what do you think? I'll reveal what's going on - at least one part of it - in the next chapter, I swear.


	3. Awakening

**[Awakening]**

"What the hell is going on here, Mr. Scott," Jim demanded as he entered the room, his gaze moving back and forth between the chief engineer and computer scientist. When none of them answered, the captain took a step closer to them. "I'll ask once again. What's going on here?"

Serena looked over at Scotty, her eyes narrowing as a warning, but the Scotsman ignored her and pointed at the monitor behind them. "She's insisting that this is the computer system of the USS Vengeance, sir," he explained, then stopped for a second and bit his lower lip. "And she's also saying that it actually says Vengeance instead of Enterprise."

"Is that so?" The captain walked past them, right to the monitor Scotty was talking about and checked a couple of things. Serena watched his back, anxiously running a hand through her hair in disbelief. Then he turned around and rested his hands on the edge of the panel. "Everything is okay with this system, Ms. Katzberg."

"But," she started defiantly before her voice faded immediately. They were looking at her as if she was insane, especially Scotty, who had called Bones anyway. She couldn't believe that they didn't see it. "I know it's not the one we use," she added, her voice suddenly rising. It wasn't right, there was no way she would mistake the two systems. "How can you tell me it's the same? I mean, if you don't see it then fine, but you can stop with that bloody game, you won!"

She was shouting now, and when Jim stepped over to put his hands on her shoulders Serena pushed him away and kept on talking. She was hysterical, sure, but she felt like she had the right to act like this, because that was an incredibly sick joke from the two men. After a minute or so, having enough of the fight, she wanted to leave the room but Jim grabbed her from behind and when she tried to get out of his hold, he only held her tighter.

Bones arrived. The good doctor didn't hesitate to inject something into her neck, but for her biggest surprise it turned out to be some kind of a tranquilizer. She didn't feel like fighting; she was completely numb, and if the captain hadn't been holding her up, she would have collapsed on the floor.

On their way to sickbay Bones kept asking questions, mainly from Scotty who tried his best to remember everything, however confusing he found it. A little bit later the engineer disappeared and there were only the three of them. Out of the corner of her eye Serena saw the raised eyebrows of the doctor as they arrived and he asked Jim to help her on the closest bed. This place was so sterile that even the idea of it made her nauseous.

"We should call Dr. Harrison," Jim spoke up as he looked over at his friend.

Serena wanted to open her mouth to stop them but she couldn't speak, and even her eyes closed from the sudden rush of tiredness.

Then Bones said something she greatly appreciated. "I don't think it would be a good idea, Jim. It would only upset her now."

"I thought they were," he started slowly, "you know."

"It's complicated, Jim, and there's something wrong with her. There are those nightmares she's having lately to begin with."

"What nightmares? God, Bones, do I really have to force it out of you?" the captain complained. "But I'll call him anyway."

"Damn it, man, don't ask for my professional advice again if you don't even listen to me."

Slowly, but she could open her eyes to look at Kirk. "Don't," she said weakly. "Don't call him. Please."

Before he could answer her, Serena fell asleep, sinking into a weird and terrifying dream again.

* * *

She was on a ship.

Probably.

But she wasn't entirely sure. The dark grey walls of the room weren't exactly modern, but apart from that, there was nothing that could help her figure out where she was. The only thing she knew for sure was the fact it was real. A hundred percent and without doubt it was real, not a dream, a creation of her own crazy mind.

Every single inch of her body was aching for some reason, but she got out of the bed anyway. Her bare feet touched the cold metal floor. It was strangely difficult to stand straight without grabbing the edge of the bed, and her legs felt weak. Probably it had been a while since she had last walked but she couldn't remember a damn thing.

Footsteps came from the hallway so she hid behind the bed as quickly as she could. It was him. The moment the man entered the room there was no question about his identity. She heard his breathing stop for a moment and, just as he turned back towards the door, she jumped up and attacked him. Serena twisted his arm without hesitation, adrenalin running through her veins to support her plan, and she slammed his face right into the nearest wall.

"Serena," he started but she cut him off immediately.

"Shut up, you son of a bitch! What the hell did you do to me?"

Khan looked at her out of the corner of his eye. "Nothing," he replied. "If you let me go I'll explain everything." She didn't move so he went on. "You have to trust me, Serena, I would never hurt you," he tried.

"Never? That's a good joke, darling," she said with a sarcastic laugh. "But at the moment I would trust the entire Federation more than you."

"What's wrong with you?"

Suddenly she let go of him, backing away until her back hit the wall. She had been so blind, believing that he had changed, even a little bit. Khan was nothing more but a tyrant; there are things that never seem to change. Family - this is what he called the others, yet it had been him who took away everything from them. So many thoughts, so many memories appeared at once in her mind.

It was too much for her, even the anger she felt couldn't make it go away. Putting her palms on the sides of her head, Serena slowly sank to the ground with her back against the wall. They had been caught and put into cryostasis again. This was the last thing she remembered. But it was a ship and they seemed to be alone. Probably he found a way to get out before they froze them.

Khan crouched down in front of her, his long forefinger running down the side of her face before stopping under her chin and pulling it up so she was looking at him. "I found a way to get out of cryostasis, but something went wrong with you," he explained quietly, his deep voice already messing with her mind. "I have to keep you asleep, Serena, right until I figure out how to help."

"No."

"Believe me," he said, "I want to help you."

* * *

"NO!"

Her heavy breathing echoed in the room as she sat up on the bed and looked around. Enterprise. Sickbay. Safety. Everything was alright and she didn't know why she screamed. There was no nightmare this time. Bones rushed into the room, John right behind him, and the two men stopped by the two sides of the bed.

"What happened?" the doctor asked as he checked her vital signs.

"I don't know," she replied honestly. One second she's falling asleep from the tranquilizer, the next she's sitting up in the bed, screaming loudly.

"Nightmare?" John offered with an unusually cold smile.

Serena had to bite her lip not to start a fight in front of the doctor. After turning her gaze to Bones, she said, "Look, I'm better now, but I'd rather go and have some rest in my room." While she was talking, she tried to get out of bed but, for her biggest surprise, it was John who gently pushed her back. "I'm fine, John. I can work in my room."

He let out a tired sigh as he leaned above her. "I would be happier if Dr. McCoy was the one telling me you're okay," he said, then straightened back, his eyes falling on the other man. "Doctor, she hasn't been herself for weeks and who knows when she will become dangerous to others."

Without saying another word or waiting for the response, John Harrison left the room, leaving two very confused people behind. Bones looked down at her with a questioning look, his hazel eyes locked with her brown ones. He didn't have to say anything; she already knew what he wanted to know.

"It's been pretty... pretty complicated between us lately," she replied. "I guess he believes I'm going insane and doesn't want a crazy girlfriend. I can understand him to be honest."

"Do you love him?"

"Doctor, it has nothing to do with this. Believe me," she added, hoping it was the truth. She couldn't be going crazy. Not because she had been having doubts about his feelings for quite some time now. "It must be something else."

* * *

**Author's note:** You're amazing! Seriously, thanks for the support. Here's a quick update - yes, I know it's short and I'm really sorry for that. And if you find typos, ignore them. I'll check the whole thing tomorrow.


End file.
